1. Field of the Invention
The present invention relates to an adapting piece of thermoplastic material. The adapting piece includes at least one welding sleeve portion with an electrical heating device. The welding sleeve portion serves to connect the adapting piece to a tubular piece.
2. Description of the Prior Art
An adapting piece of the above-described type of thermoplastic material in the form of a T piece is known from AT-B-203 202. This T piece is provided with welding sleeve portions with electrical heating devices for connecting the adapting piece to pipes. The adapting piece is an injection molded piece in which annular heating elements are embedded, so that the manufacture of the adapting piece by injection molding is very complicated and expensive. Due to diameter tolerances which may exist in the pipes and in the sleeve portions of the adapting piece, it is possible that the welding connections between the pipes and the sleeve portions are insufficient or untight because a welding pressure cannot be built up. In addition, due to the play existing between the pipes and the welding sleeves, it is necessary to provide devices for supporting the pipes and adapting piece during the welding process. Such devices require a substantial amount of space. This space is not available in the case of sanitary installations where the pipes must be placed in narrow wall recesses.
EP-Bl-0036 963 discloses a welding sleeve in which the welding pressure required for a tight and secure welding connection is obtained by releasing a frozen-in shrinkage stress during welding. However, in this welding sleeve, devices are required for fixing the sleeve during the welding process. If the welding sleeve is used for supply lines which are installed outdoors, this requirement of a fixing device is not a considerable disadvantage.
It is, therefore, the primary object of the present invention to provide an adapting piece of the above-mentioned type which can be installed by fixing it before and during the welding process without additional devices within very narrow space relative to the pipes or tubular pieces to which it is to be connected. In addition, a tight and secure welding connection is to be ensured, so that the adapting piece can be used in pressure pipe systems, such as, cold water and warm water pipes in sanitary installations.